Bellarie VP 129 mod

[faxurda]

Some one got this schematic.. I planning to modifiy this phono preamp.

Thanks

[faxurda]

Ok No body got this schematic!!! So I started Oamp swap... (on red on the picture). I put 2 LM4562NA. The channel separation is amazing and the floor noise drop close to none.....

Next mod I wanted changed the coupling cap... And the other Oamp with the same LM4562NA.



I presume the coupling cap is one of those show on the picture.

1&3 10 uf
2&4 47 uf

Some one know.

ps: Is my first mod experience...

[trondkj]

You can find the schematic on this link: Bellari
vp129

[faxurda]

Thanks . This is a really god help

[faxurda]

I whant to change the coupling capacitor (C11, C22)
my choice is
Mundorf M-CAP or Elna Cerafine or Simlic II, any comments ... I know Black Gate but It's hard to find what we need..

And The c2 & c13 is suitable to chage for a better cap ?

And of course all resistors will be change for metal type 1% tolerance , PSU cap for Panasonic or Elna or Muse..

[faxurda]

Ok I choose my cap.

I go with Elna Cerafine for power supply cap.
For c2 & c13 and coupling capacitor I got 2 choice in my price range.

1. SOLEN film & Foil Fast cap. ( https://www.solen.ca/pdf/solen/foilcap.pdf ).

2. Mundorf M-CAP

Please advise me on my choice is my first attent modification.

Thanks.

[faxurda]

If I put the ba4560 in u1/u2 and lm4562 in u3/u4 position I got nice sound.

But

If I put the lm4562 in u1/u2 and the ba4560 in u3/u4 no sound comming from the preamp....

I will look futher in the in put circuit bettwen the buffer tube and the first amp.. I thinking about the imput impedance..

Do i need change someting to the design ? or try different opamp?

http://avforum.no/forum/attachments...llari-vp129.pdf

[faxurda]

At this point I replaced my output cap with 4.7uf Mundorf M-Cap, 100uf Muse cap on c23 position (this change is amazing).

Ok in the pass day I read about opamp, thanks’ to TI documentation..

LM4562 is at the output stage. But I got to much floor noise... I read on some forum the LM4562 don't like big resistor as feedback.

So I was thinking to replace the original 47k on r32/r15 for 15k and the 4.7k at r31/r14 for 1.5k.

My only concert about this change is it will be safe? Because the +vb is in the entrance of the opamp. Please help me with this one.

And I need to add bypass capacitor on the lm4562 on the power supply. I will put 47uf like they show in the datasheet..

[planarboy]

How's the headphone out on this baby?
If I were to make my brother a low cost system for headphones, would anyone recommend this as a great pre and headphone amp combo? I have a guy who can do the probably necessary mods...this'd be a great cost cutter for a modest system...lose the price of a component and a pair of IC's. Can they run, say, the sennheiser hd555's, lo-lo/med price audiophile cans. I don't love him that much.
dave

[faxurda]

I almost done with my extreme mod for this preamp.

On the RIAA I used the opamp 2134 but ... I don't really like it . I try to sawp with LME49720 but the pre-amp stay silent. Im not a opamp expert. So I need help to put the LME49720 in the RIAA section.

Thaks